net: ethernet: davinci_emac: Use MAC Address from Device Tree

Currently there is a device tree entry called "local-mac-address"
which can be filled by the bootloader or manually set.This is
useful when the user does not want to use the MAC address
programmed into the SoC.

Currently, the davinci_emac reads the MAC from the DT, copies
it from pdata->mac_addr to priv->mac_addr, then blindly overwrites
it by reading from registers in the SoC, and falls back to a
random MAC if it's still not valid.  This completely ignores any
MAC address in the device tree.

In order to use the local-mac-address, check to see if the contents
of priv->mac_addr are valid before falling back to reading from the
SoC when the MAC address is not valid.
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20231022151911.4279-1-aford173@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/ti/davinci_emac.c

@@ -1928,18 +1928,20 @@ static int davinci_emac_probe(struct platform_device *pdev)
 		goto err_free_rxchan;
 	ndev->irq = rc;
 
-	rc = davinci_emac_try_get_mac(pdev, res_ctrl ? 0 : 1, priv->mac_addr);
-	if (!rc)
-		eth_hw_addr_set(ndev, priv->mac_addr);
-
+	/* If the MAC address is not present, read the registers from the SoC */
 	if (!is_valid_ether_addr(priv->mac_addr)) {
-		/* Use random MAC if still none obtained. */
-		eth_hw_addr_random(ndev);
-		memcpy(priv->mac_addr, ndev->dev_addr, ndev->addr_len);
-		dev_warn(&pdev->dev, "using random MAC addr: %pM\n",
-			 priv->mac_addr);
+		rc = davinci_emac_try_get_mac(pdev, res_ctrl ? 0 : 1, priv->mac_addr);
+		if (!rc)
+			eth_hw_addr_set(ndev, priv->mac_addr);
+
+		if (!is_valid_ether_addr(priv->mac_addr)) {
+			/* Use random MAC if still none obtained. */
+			eth_hw_addr_random(ndev);
+			memcpy(priv->mac_addr, ndev->dev_addr, ndev->addr_len);
+			dev_warn(&pdev->dev, "using random MAC addr: %pM\n",
+				 priv->mac_addr);
+		}
 	}
-
 	ndev->netdev_ops = &emac_netdev_ops;
 	ndev->ethtool_ops = &ethtool_ops;
 	netif_napi_add(ndev, &priv->napi, emac_poll);